ruler

noun

rul·​er ˈrü-lər 

1

: one that rules

specifically : sovereign

2

: a worker or a machine that rules paper

3

: a smooth-edged strip (as of wood or metal) that is usually marked off in units (such as inches) and is used as a straightedge or for measuring

rulership

ˈrü-lər-ˌship 

noun

Synonyms

• autocrat
• monarch
• potentate
• sovereign
• sovran

Examples of ruler in a Sentence

a summit attended by a number of rulers from around the world

This ruler shows inches and centimeters.

Recent Examples on the Web

Much like the moon — which happens to be Cancer's planetary ruler — Mary has an emotional pull that stirs something deep in those around her, effortlessly drawing them into her orbit with her heartfelt sincerity and loving nature. —Athena Sobhan, People.com, 16 Jan. 2025

Throughout history, individual rulers and emperors have attempted to control, heavily tax, and even halt trade along the Silk Roads. —Christian Catalini, Forbes, 16 Jan. 2025

The center section has a keychain hole and ceramic window-breaking stud at one end, a ruler along one side (albeit one with no numbers), and a large pry bar at the other end. —Ben Coxworth, New Atlas, 16 Jan. 2025

Among the hoard is Eugenius, an infamous ruler considered illegitimate by the Eastern Roman Empire, also known as the Byzantine Empire. —Andrea Margolis, Fox News, 15 Jan. 2025

Word History

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing ruler

• co-ruler

Kids Definition

ruler

noun

rul·​er ˈrü-lər 

1

: sovereign entry 1 sense 1

2

: a straight strip of material (as wood or metal) marked off in units and used as a guide in drawing lines or for measuring